I agree with Erin on two points. First, you are the only one truly responsible for your health, and some decisions you have to make alone. Ultimately, it is your life, and life without good health isn’t worth much. Second, the number on the scale isn’t always a good indicator of what’s happening. You’ll have to decide whether the weight gain is healthy tissue or just unneeded fat.
On the other hand, it’s worth listening to your husband’s concerns, because I’m sure he cares about your health too. My wife also gave me some grief when I put on some extra weight, and I wasn’t happy about it, but now I know that she was right (even if I don’t like how she went about telling me!).
Finally, your husband might feel that he is protecting you from doing damage to yourself, and he probably doesn’t understand why you are making a sudden change. It’s natural for him to be worried, although I do hope he is communicating that worry in a respectful way.